Memory device and power management method using the same

A memory device that is operable at a first voltage domain and a second voltage domain includes a memory array, a power saving mode pin and a word line level shifter circuit. The memory array operates at the first voltage domain. The power saving mode pin is configured to receive a power saving mode enable signal that is at the second voltage domain. The power saving mode enable signal is configured to enable a power saving mode of the memory device. The word line level shifter circuit is coupled to the memory array and the power saving mode pin, and is configured to clamp a word line of the memory array to a predetermined voltage level that corresponds to a first logic state during the power saving mode of the memory device.